US1428999A - Gradually variable power-transmission gear or drive - Google Patents

Description

J. AND E A. TYGARD.

GRADUALLY VARIABLE POWER TRANSMISSION GEAR 0R DRIVE.

APPLICATION FILED NOV. 29.1921.

Patented Sept.

7 SHEETSSHEET l l. W. AND E. A. TYGARD.

GRADUALLY VARIABLE POWER TRANSMISSION GEAR 0R DRIVE.

APPLICATION FILED NOV. 29, I921.

PatentedSept. 12, 1922.

2 SHEETSSHEET 2 Patented Sept. 12, 1922.

UNITED STATES PATENT OFFICE.

JAMES WALLACE TYGARI) .AND ELIZABETH ANN TYGABD, OE LONDON, ENGLAND.

GRADUALLY VARIABLE POWER-TRANSIIISSION GEAR OR DRIVE.

Application filed November 29, 1921.

To all whom it may concern Be it known that we, James lVALLAcm TY- cam) and Emznnn'rn ANN Trellis), both citizens of the United States of America, and both residing at Tygard House, 21 Old Gloucester Street, London, W. C. 1, England, have invented a certain new and useful Gradually Variable Power-Transmission Gear or Drive, of which the following is a specification.

This invention relates to power transmission gear of the type wherein the power is transmitted from a rotary element to a rotary element by means of a transmission or driving connection in the form of a chain or belt.

An object of the invention is to provide a variable gear or drive capable of transmitting power at two or more speeds, in which the change from one speed to another is eifected gradually while the elements are rotating and without in any way interrupting the continuous transmission of power.

The invention comprises a driving or a driven unitprovided with a plurality of transmission engaging members arranged around the axis of the unit or units and capable of displacement into and out of a position in which they may be engaged by the transmission connection as the rotation of the unit progresses, so that the transmission of power may be transferred from transmission engaging members situated on a circle of one radius to transmission engaging members situated on another circle at anotherradius or other circles of other radii.

The transmission engaging members may be displaceable in an axial or longitudinal direction, in which case a series of coaxial sets of elements are provided. Alternatively one or more coaxial sets of elements may be displaceable from one radius to another in a straight or curved path; or a combination of these two modes of displacement may be adopted.

The transmission engaging members are displaced during that part of the arc of roation in which they are free from engagement with the transmission connection, and

Serial No. 518,741.

means are provided which are adapted to displace the elements during this period in their rotation.

The transmission or driving connection may be a frictional transmission connection such as a belt or it may be of chain form, according to the application of the invention. If the connection be of chain form it may be a sprocket chain or a chain of the inverted tooth type generally known as a silent chain; or the chain may be of any other form adapted positively to engage driving or driven elements.

For the purpose of driving or transmitting power in a reverse direction to that for which the gear is normally designed, the driving and the driven units or elements are combined with spur or like positive gears, or if the gear be designed for belt transmission the elements may be combined with pulleys and a crossed belt employed.

Hereinafter the transmission engaging member may be referred to for brevity as the transmission member or, in certain cases, by the term member.

lV hen the invention is applied to either the driving or the driven element alone, a jockey pulley or roller may be employed in connection with the belt or chain in order to take or give up the slack as occasion arises when the speed of transmission is varied.

For the purpose of indicating ones suitable way in which the invention may be carried into effect, a unit which may be employed either as a driven or a driving unit will now be described, but for convenience the unit will be considered from the point of view of a driving unit.

In the accompanying drawings Figure l is a diagrammatic elevation illustrating transmission units according to one form of the invention. The right-hand unit in this figure is shown with a fixed set of transmission engaging members but it is to be understood that both elements may, if

desired, be provided with movable transmission engaging members.

Figure 2 is a diagrammatic sectional plan of a driving or driven unit which, for. the

purpose of description, will be referred to as a driving unit, the driven unit in this figure being omitted, a pinion alone being frame or base 6.

shown for effecting the reverse drive.

Figure 3 is a diagrammatic developed plan of a switch device for use in association with the outer set of transmission engaging members shown in Figures-1 and 2, while Figure 4 is a similar view of a switch device for use in association with the inner set of transmission engaging members shown in Figures 2 and 3.

In carrying the invention into effect ac cording to one convenient mode, as applied to a driving unit tilapted to' itivide a high and low speed ratio a 1' ave and a neutral or coasting position,-'a' central or main driving shaft 1 has keyed'up'on it a cylindric leasing or housing, 2 preferably clivid'edfinto two parts '8 and 4. The'casing has a central cavity in which is located an annular element harried by a stationary Within the annular element 5 a hub member 7 issecured to the casing 2 or keyed upon the shaft 1.

For this driving unit two coaxialsets or series of transmission engaging members are provided. An outer set 8 is mounted within the part 4 ofthe'casing 2 and between the part 3 of the casing and the annular element 5. The inner set or series of transmission engaging elements 9 is similarly mounted in the part 40f the casing and between the annular element 5 and the hub member 7.

Each of the transmission engaging elements comprises a steel rod 8, 9, of circular cross-section having 'a wheel or runner 8 or 9 preferably of the shape indicated. The cylindrical parts of the rods 8 and 9 are supportedin and guided by holes in the part 4 of the casing 2 on the one hand and on the other in semicircularslots formed in'the part 3 of the casing 2 and the hub member 7 respectively.

The casing 2 is provided with a ch ain, hub or plane cylindrical portion 10 extending axially from it. This hub 10 is formed with an outer flange or disc 11. The clearance between the outer wall of the casing 2 and the inner wall of the flange or disc 11 is such as to accommodate a transmission connection in the form of a chain 12. Two coucentric sets of holes 18 and 14 are provided, each hole of which is arranged coaxially with its corresponding transmission rod of the sets 8 and 9 and these holes are adapted to accommodate and support the ends of the rods when the latter are in their outer position, as will be presently described.

The parts 3 and 4 of the casing 2 and the hub 7 are recessed to form races 14 and 15 for the travel of the wheels or runners 8 and 9 respectively.

The fixed annular element 5 upon its outer periphery is formed with two tracks 'or grooves 16 and 17 of V shape or a crosssection corresponding with that of the runners. the track 16 the transmission rods 8 are in the idle position and when the runners are travelling in the track 17 the rods are in the protruded position with their ends engaged and supported in the holes 13 in the flange or disc 11.

On the inner peripheral surface of the annular member 5 three tracks 18, 19 and 20 for the runners 9 are formed. The track 18 is in the same plane as the track 16 and corresponds with the reverse position of the set of rods 95 so far as'the chain is concerned, and is in an idle position. When the runners 9 are in the track 18 their ends remote from the chain are protruded from the casing to engage the pinion21 for transmitting a reverse drive to the driven shaft 22 upon which the pinion 21 is keyed. The track 20 is in the same plane as the track 17 and corresponds with the position of the rods 9 when they are in their outer or protruded position, and extend across the plane o fthe chain with their ends engaged in the holes 14 in'the disc 11. The track 19 is located intermediate the tracks 16 and 17 and affords a second idle position for the rods 9 withrespect to the'chain 12.

The tracks 16 and 17 are interrupted by a recessed portion such as 28, the surface of which is a part of a cylinder having the same axis as the shaft 1. This surface coincides with and forms anextens on of the lowest point of eachof the grooves '16 and 17 so that the runners in their travel from the part of tracks 16, 17 upon one side of this portion 23 to the tracks on the other side pass across the cylindrical surface 23.

A similar interruption 24 (Figure '4) is provided in connection with the three tracks 18, 19 and. 20, and in both of these interrupted portions 23 and 24 a switch is located which is adapted to'transfer at appropriate times, the runners of the transmission engaging elements from one track to another in order to cause the appropriate axial movement of such elements required to effect the change of gear desired. The interrupted portions 23 and 24 and their switch devices are located in the arc of the circumference of the unit which is free of the arcuate lap of the chain.

The switch for the runners 8 is shown in Figure 3 at 25 and this switch is adapted either to transfer the runners 8* from the track 16 to the track 17 or from the track '17 to the track 16. The switch 25 for the runners 9* employed 1n connection with the tracks 18, 19 and 20 comprises two parts or elements 26 and 27 mounted upon a boss or head which is flush with the surface 24. The parts 26 and W hen the runners 8"are moving in 27 are mounted so that a space 29 is left between them for the passage of the runners 9 when moving into or travelling in the track 19.

The switch 25 may be placed in a position to cause the runners to be passed from one track to another, according to the position of gear desired, as will be hereinafter described. A

The two switches 25 and 25* are mounted upon the opposite ends of the same spindle having suitable hearings in the annulus 5. The center of this spindle is preferably provided with a worm-wheel 30 adapted to be engaged by a worm such 30" mounted on the end of a rod 31 which is operable from the outside. By rotating the rod 31 the position of the switches on the runners 8 and 9 may be altered at will.

It will be observed from the foregoing description that as the driving shaft 1 rotates (counter-clockwise according to Figure 1) the casing 2 with its parts 3 and 1- and the hub member 7 rotate en bloc carrying with them the two sets of transmission rods 8 and 9, so that the latter have a planetary movement around the axis of the shaft 1, travelling in one track or another, according to the position of the switches.

Then a change of the nature of the gear ratio is to be performed the particular switch element or switch elements is. or are introduced across the particular track or tracks in question. The point of a switch operates first by moving a transmission rod free of the chain over to one side slightly by hearing against its runner. This slight lateral movement afiords sufiicient margin for the introduction of the extremity of the switch element across the track or the oncoming runners. The switch operates as a facing point and causes each runner in succession .to follow an inclined path. The runner bears against and slides upon the operative face of the switch. This movement causes the transmission rods to move or slide in succession axially so that their outer ends occupy the position required according to the change of condition to be effected.

To take an example, assumingit be de sired to change from the reverse as shown in Figure 2 to low gear position. The rod 31 is operated so that the switches are rotated upon their axes. The switch point 26 is introduced across the track 18 with the result that each runner in succession will enthe inner face of the switch and be ferring-them to the track 20 in which the ends of the set or rods 9 lie in the plane oi the chain between the disc 11 and the end of the casing. 2. In this position it will be seen that the element 26 will occupy a position still further to the left in Figure 1 but as there are no runners travelling in the track 18 this is of no consequence. Moreover, the corresponding movement of the switch 25 will be idle as the runners 8 are still travelling in the track 16.

v To take another example, supposing it is desired to change "from the low to high speed ratio, the rod 31 is operated to move the switch 25 over into a position in which .it cuts the track 16. The runners 8 will in succession travel into the track 17 in which position the ends of the rods lie under the chain. As this axial movement of the rod is progressive the chain is picked up and lifted from off the rods 9 as the revolution of the unit progresses.

In moving the switch 25 as the switch 25 is moved into the position above indi cated, the switch elements 26 and 27 are thrust still further into an extreme position to the left, both switch elements 26 and 27 lying across the tracks 18 and 19 but as these tracks are free of runners the movement is without eli'ect as is, of course, required.

Assuming, now. that it is desired to change gear from the high gear to a neutral or coasting position, the switch 25 is moved over to cut the track 17 and subsequently moved still "further over to the right until the switch element 27 cuts the track 20. By this operation it will be seen that first the track .17 is cleared of runners which are trans- .fGIl'QCl to the track 16 and secondly the run- '9 are protruded into a position in which. they mesh with the gear 21, as shown in Figure 2. 7

l laving now described our invention what we claim as new and desire to secure by Letters Patent is 1. A variable power transmission gear comprising a rotary element, a plurality of concentric sets of transmission engaging members arranged around. the axis oi the rotary element, the engaging members oi the several sets being capable of displacement into and out of a position in which they may be engaged by a transmission con.-

' nection'as the rotationof the Yeleinent progresses so'that the transmission of-Ipowerimay be transferred from a set oil transmission.

engaging members situated on a circle of one radius toa set of transmissionengaging gaging members'situated on another circle or another radius. I

2. A; variable vpower transmission gear comprising a rotary'element, a-plurality of concentric sets of transmission engaging members arranged around the axis of the rotary element, the engagingmembers of the several sets being'capable of axial displacement into and out or a position in which they may be engaged by a transmission connection as the rotation of the element, progrosses whereby the transmission of power may be transferred from a set of'tr'ansmission engaging members situated on one circle of one radius to a set of transmission engaging members sit'uated on another circle or another radius.

a 8. A variable'power transmission gear comprising a rotary element, movable transmission engaging members arranged in a plurality of series of coaxial setsand means coacti'ng with "said transmission engaging members of the sever'al' sets whereby the transmission of power may be transferred from aset of transmission engaging "members situatedon a circle of one radius to a set of transmission engaging members situated on a circle of'another radius.

4. A variable power transmission gear comprising afrot'atable element, a plurality of annular sets of planetary transmission engaging members, the'engaging members of each set being capable of axial displacement in succession into and outer a position in which they may be engaged by a transmission connection asthe rotation of the unitprogresses, and means tOreft'ect-ing displacement of the transmission engaging members at a time when they are disengaged from the transmission connection. 7

5. *A variable power transmission gear comprising a rotary element, a plurality of planetary transmission engaging members ca- :pable of axial. movement into and out of operative re'lationto a transmission connection, a switching device associated with the trans mission engaging members, "and meanson "said transmission engaging members located intermediate the ends thereof and engageable by said switching device whereby said members are moved axially from one 'position to another. 6. A variable power transmission gear comprising a rotary elementand a plurality of setsot planetarytransmission engaging members movable axially 'into and out of operative relation-to a transmission connection during the rotation of said element, circular tracks having portions thereof interrupted projections on said transmission members associated with one set causes'the planetary transmission engaging members-i mounted for: axial 1 displacement and arranged'in a series of coaxialsetsy said transmission engaging members being adapted for engagement with a transmission connection, and means for displacing the sets of.

said transmission engaging members, the displacing means from the several sets ot transmission engaging members being connected together so that the displacing transmission connection: to engage trans mission members of this set at' a greater radius, the displacing means associated with the other set causes the transmission 'con-.

:nection to engage transmission members-of i that set at a correspondingly -less radius.

8. A variable power transmission gear comprising a. rotary element, a plurality of transmission engaging members mounted for axial displacement in s'u'ccessioninto and out of. position for engaging a transmission connection, and a gear iengageable by certain ot'the transmission members to effect a reverse drive. r

9. A variable. power transmission gearcomprising a rotary element, a plurality of circular sets of transmission engaging members each movably mounted in the-rotary element, the respective se'ts of transmission members being selectively engageable .with-' transmission connections and-the several sets or transmission members being of ditterent length.

10. A variable power transmission gear comprising a plurality of transmission ,engagingmembers mounted for displacement into and out or position for-.engaginga transmission connection a support for said membersyand a plain surtacemember car-' ried by the support and arranged in the p plane of the transmission connection whereby, when the transmission engaging 'members are displaced out "of the planev of the transmission connection, a neutral state of the gear isprovided' 11. A variable power transmission gear comprislng-a rotary element; a pluralityv of *setsof transmission engaging members, the

several 'setsot transmission engaging members being concentrically spaced and ar-- ranged about theaxis of the rotary element,

and means operable to projecteither set-0t engaging members 1nto transmission con-v nection engaging position and to simultaneously retracttheengaging members 'ofthe" several sets whereby to disengage said members from the transmission connection.

12. A variable power transmission gear comprising a rotary element, a plurality of sets of planetary transmission engaging members, the several sets of engaging members being concentrically spaced and arranged about the axis of the rotary element and being capable of movement into and out of operative relation to a transmission connection during rotation of said element, circular tracks having portions thereof interrupted, projections on said engaging members adapted to travel in said tracks, switching devices arranged in the interrupted portions of the track arranged to engage with the projections on the transmission engaging members of the respective sets whereby to successively transfer the latter from one track to another and a pivotal support common to the several switching devices whereby the latter are simultaneously actuated.

13. A variable power transmission gear comprising a rotary element, a plurality of sets of planetary transmission engaging members, the several sets of engaging members being concentrically spaced and arranged about the aXis of the rotary element and being capable of movement into and out of operative relation to a transmission connection during rotation of said element, circular tracks having portions thereof interrupted, projections on said engaging members adapted to travel in said tracks, switching devices arranged in the interrupted portions of the track arranged to engage with the projections on the transmission engaging members of the respective sets whereby to successively transfer the latter from one track to another, a pivotal support common to the several switching devices whereby the latter are simultaneously actuated, and means for adjusting said supporting means for varying the position of the switching devices.

In testimony whereof we have signed our names to this specification.

JAMES WALLACE TYGARD. ELIZABETH ANN TYGARD.

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